phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('907499c5ecf694f72d4ad9fcef073add', -1, 1498140816, 1498140816, '17143596', 7, 0, 0)

Line : 189
File : sessions.php